Rotary offset printing press with gripper cages



Jan. .11, 1955 w. w. DAVIDSON, JR

ROTARY OFFSET PRINTING PRESS WITH GRIPPER CAGES Filed May 2, 1950 IN VEN TOR.

n- 11, 1955 w. w. DAVIDSON, JR 2,699J 1 5 ROTARY OFFSET PRINTING PRESS WITH GRIPPER CAGES Filed May 2, 1950 5 Sheets-Sheet 2 I i INVENTOR.

Jan.- 11, 1955 w. w. DAVIDSON, JR 2,699,115

I ROTARY QFFSET PRINTING PRESS WITH GRIPPER CAGES 7 Filed May 2, 1950 5 Sheets-Sheet 3 W- W. DAVIDSON, ,JR

Jan. 11, 1955 ROTARY OFFSET PRINTING PRESS WITH GRIPPER CAGES 5 Sheets-Sheet 4 Filed May 2, 1950 INVENTOR.

Jan. 11, 1955 w. w. DAVIDSON, JR 2,699,115

ROTARY OFFSET PRINTING PRESS WITH GRIPPER CAGES Filed May 2, 1950 5 Shets-Sheet 5 H 62 INVENTOR. L i i United States Patent ROTARY OFFSET PRINTING PRESS WITH GRIPPER CAGES William W. Davidson, Jr., Evanston, Ill. Application May 2, 1950, Serial No. 159,591 18 Claims. (Cl. 101-232) Rotary lithographic presses of old usually included three cylinders, namely, a plate roll, a blanket roll and a platen roll. The plate roll carried the plate which was dampened and inked by running past dampening and 1nk1ng rolls, and then printed the image on a blanket on the blanket roll. The blanket then printed the image on the sheet being printed while it was backed up by the platen roll.

Two-cylinder lithographic presses have been known for many years and have recently met with considerable favor. In these the plate and platen are on opposite sides of one large drum. The blanket roll, of half this size, makes a first revolution against the plate to receive the ink image, its next revolution rolling against the platen to print a sheet which passes between them.

For dependable quality, this form of two-cylinder press requires a gripper bar to pass through the bite between the drums at the correct time to carry the sheet into the desired registration with the blanket during its printing revolution. Various means for accomplishing this have been used. When the gripper bar is mounted on the blanket roll it is of no aid in stripping the sheet from the blanket. When it is mounted on the large drum, it is of no aid in stripping from that drum if that drum is occasionally used for direct printing of the sheets, and other faults are encountered in any event. Chain-carried grippers have been used, but chains are noisy, especially after wear, wear the sprockets, change their own length with wear, present registration difliculties in some instances, and have other faults.

According to the present invention, the gripper bar is carried through the printing bite and away from both rolls by a rotary rigid cage including a pair of rims or rings lying just beyond the ends of the blanket roll and having a larger diameter. Such rings run quietly, substantially without wear or other change, may be timed accurately by direct gearing and have other advantages.

Some advantages flow from the fact that the rigidity and constancy of the gripper cage permit feeding the sheet to the grippers at a point remote from the bite and spaced from both rolls. This in turn has two quite different advantages: (a) The registration feed roll mechanism can be simplified because the increased room available for it permits the use of one or more large feed rolls or segments of rolls, and (b) The accessibility of the cylinders for washing and other servicing can be increased.

The axis of the blanket drum necessarily passes through the circle surrounded by the rim peripheries. This necessarily poses a problem of mounting and driving the blanket drum. Two solutions have been shown, though others as well as various combinations of these two will readily suggest themselves. According to one, the rims are carried by hubs at their centers, running on stationary stub shafts, the inner ends of which shafts are extended inwardly to form a solid stationary bracket between the rings. The blanket drum is rotatably supported by arms extending from this bracket and driven through one of these arms from a gear carried by the hub of one of the rings. According to the other solution shown, the rims are mere annular or hubless rings rotatably carried by peripheral bearing wheels. The usual support and drive for the blanket drum extends through the center hole in the ring.

Additional objects and advantages of the invention will be apparent from the following description and from the drawings.

Designation of figures Figure 1 is a somewhat diagrammatic, vertical, sectional view taken longitudinally through one form of the press chosen for illustration,

Figure 2 is a plan view, partly broken away, of the structure seen in Figure 1,

Figure 3 is a fragmentary, horizontal sectional view taken approximately on the irregular line 3-3 of Figure 1,

Figure 4 is a fragmentary, somewhat diagrammatic vertical sectional view taken approximately on the line 4-4 of Figure 3, showing also the use of a second gripper unit,

Figure 5 is a somewhat diagrammatic detail view showing one form of the drive for the feed roll mechanism,

Figure 5-A is a diagrammatic representation of a modified arrangement of the parts especially suitable for a table model, and

Figures 6 and 7 are fragmentary diagrammatic views of a modified form of the invention, showing respectively a vertical longitudinal section and a plan view with parts removed for clarity.

Although the law requires a full and exact description of at least one form of the invention, such as that which follows, it is, of course, the purpose of a patent to cover each new inventive concept therein, no matter how it may later be disguised by variations in form or additions of further improvements; and the appended claims are intended to accomplish this purpose by particularly pointing out the parts, improvements or combinations in which the inventive concepts are found.

General description The presses of the present invention include two press cylinders 11 and 12, the cylinder 12 being twice as large as the cylinder 11. The cylinder 12 includes a platecarrying portion 13 and a platen portion 14 which roll against the cylinder 11 during successive revolutions thereof. The cylinder 11 has a blanket 16 (Figs. 1 and 4) which receives an ink impression from plate 17 on the plate-carrying portion 13 of cylinder 12 and in turn applies this ink impression to a sheet to be printed, backed up by the platen portion 14. The sheet is delivered to the cylinders with proper timing by a gripper unit 18 carried by a cage 20, which in Figs. 1 to 4 includes wheels or rims 19 at opposite sides of the press. The sheets are successively fed to the gripper units 18 by registration feed unit 21. Dampening fluid and ink are successively applied to the plate 17 by dampener assembly 22 and inker assembly 23. Cam prevents their engaging platen 14. The registration feed roll unit 21, the cage 20, the blanket cylinder 11, the plate and platen cylinder 12, and the dampening and inking assemblies are all driven in timed relationship by means which include gears between the various main rotating elements. The present invention is particularly concerned with the cage structure carrying grippers 18, with the registration feed roll unit 21, and with the over-all arrangement of the several elements to provide ready accessibility to all necessary parts of the press.

Gripper bar carrier A feature of the present invention is that the gripper 18 rigidly revolves around the blanket cylinder 11, following an orbit larger than the blanket cylinder, so that it may feed the sheet to and strip it from the blanket cylinder. By the expression rigidly revolving is meant that the gripper is part of a rigid cage rotating about a fixed axis so that the action of the gripper may be accurately predetermined. Heretofore, grippers which passed around the axis of the ink-applying cylinder have either been carried directly by the cylinder so that they could perform no feeding or stripping function, or they have been carried by chains with the result that their positioning from time "to time was not certain to be invariable and various expedients had to be resorted to to obtain reasonably accurate registration of the sheets with the printing cylinders.

In the form of the invention shown particularly in Figs. 1 to 4, the gripper 18 is carried by wheels 19, each of which rotates about a stationary stub shaft 26. The stub shafts are rigidly secured to frame members 27, which may be either part of the main press frame or an attachment secured thereto. Two methods of securing the stub shafts 26 have been illustrated in Fig. 3. At the upper part of the figure, the stub shaft 26 has been shown with a flattened portion 28. Such flattened portions would be provided on the upper and lower portions of the shaft 26 so that the shaft could be cla iped to a flat seat on frame member 27. Such clamping could be accomplished either by bolts 29 passing through the shaft 26 or by a clamp plate engaging the upper flattened portion of the shaft. At the bottom portion of Fig. 3, the shaft 26 has been shown as having a splined engagement with the frame member 27. The splining gives greater certainty of the absolute angular rigidity required and is the preferred form at present.

The wheel 19 shown at the lower portion of Fig. 3 is provided with gear teeth 31 which mesh with gear 32, which is the main gear for the large cylinder 12. Thus the wheel 19 with its teeth may be deemed a gear having the same number of teeth and the same pitch diameter as the gear 32 so that the two rotate constantly at a 1:1 ratio. The for wheel 19 rotates with the gear wheel 19, being rigidly connected thereto through the bar 34 of gripper unit 118 and a second bar 33. The second bar 33 may be a gripper unit like the gripper unit 18 and in some forms of the invention this may be quite advantageous. in the simplest forms of the invention, however, there will be only one gripper unit 18 and the bar 33 would be merely a brace to help ensure rigidity of the gripper cage. It will be observed that the two wheels 19, together with the bar 33 and the bar portion 34 of gripper unit 18, comprise a rigid rotating cage similar to a squirrel cage.

It may be noted at this point that the gripper unit itself is reasonably conventional. In addition to the main bar portion 34, it includes a shaft 36 (Fig. 4) which carries gripper fingers 37 and is rocked by crank arm 38 (Fig. 3) carrying a cam follower roller 39. Gripper earns 41 and 42 open the gripper fingers 37 at the desired times and permit them to close under influence of a spring, not shown. Arm 38 may trail and be pushed out by suitable cams instead of leading and being pushed in by earns 41 and 42, as illustrated.

Mounting f blanket cylinder When a gripper cage is provided which rotates on stub shafts 26 as in the form of invention in Figs. 1 to 4, it is impossible to extend a shaft for blanket cylinder 11 to the main frame members. Accordingly stub shafts 26 carry bracket arms 43 and 44 integrally connected together by the main carrying bracket 46. Preferably the main carrying bracket 46, bracket arms 43 and 44, and stub shafts 26 form one casting or at least one unitary rigid structure so that the stub shafts 26 are not cantilever shafts but are part of a beam structure extending between opposite frame members 27.

A shaft 48 for the blanket cylinder 11 is journaled in bracket arms 43 and 44. Blanket cylinder 11 is keyed to shaft 48. At the end of shaft 48 extending through bracket arm 44, a pinion 49 is keyed to the shaft 48. This pinion 49 is driven by pinion 51 carried on and keyed to the hub of gear wheel 19. The drive between pinions 51 and 49 is indirect, through an idler pinion 52, as seen best in Fig. 4. Thus the cylinder 11 rotates in the same direction as the gear wheel 19. The pinion 51 has twice the number of teeth and twice the pitch diameter as pinion 49 and the pinion 51 turns with gear 31 which, as previously stated, turns 1:1 with gear 32 and hence the cylinder 11 makes two revolutions for each revolution of cylinder 12.

Alignment, pressure and throwout provisions A printing press should have an adjustment for aligning the axes of its cylinders to provide uniform printing pressure across the width of the cylinders. It should also have an adjustment of one cylinder toward the other for adjusting the amount of this uniform pressure. The means for providing this latter adjustment may be a part of the mechanism used in separating the cylinders whenever a sheet is skipped so that the blanket will not print onto the bare platen surface. In the form of press shown in Figs. 1 to 4. all of these adjustments have been provided in connection with the large cylinder 12. 1t

is not necessary to describe these in detail because the mounting could be such as provided in many prior presses. To indicate one type of known mounting contemplated, a brief description may be desirable. An eccentricallybored bushing 56 may be turned to provide the alignment adjustment. This does not shift the axis of gear 32 rotating on the outside of this bushing and hence gear 32 always meshes properly with gear 31 on wheel 19 and other meshing gears. Turning bushing 56 does, however, shift one end of shaft 57 to produce the aligning adjustment. Shaft 57 does not rotate with the cylinder 12 but may be rotated slightly by lever 58 to vary the spacing of the cylinders. A slight movement is enough for pressure adjustment. A larger movement provides the throwout for separation of the cylinders in case a sheet is skipped. (No attempt has been made to show the exact degree or angularity of eccentricity.) For example, lever 58 may be slightly adjusted for pressure adjustment and connected by linkage to suitable platen throwout and sheet skip detection means. The cylinder 12 is driven by gear 32 through any type of Oldham coupling, diagrammatically represented at 59.

Preferably, the driven ring 60 of the Oldham coupling is adjustably connected to the end plate 61 of cylinder 12. Thus a bolt. 62 may extend through an arcuate slot 63 in ring 60 and screw into the end plate 61. Tightening the bolt 62 locks the coupling ring 60 and the end plate 61 provides adjustment of the angular relationship between cylinders 11 and 12. This adjustment varies the position on the blanket of the impression placed thereon by the plate. Hence this provides a head-margin adjustmom of the printing on the sheet. The circumferential extent of the platen must be long enough to accommodate the desircd length of sheet, regardless of this adjustment. Hence with this type of head-margin adjustment, it is desirable to have the platen somewhat longer than the plate-carrying portion, the gripper unit 18 while gripping the sheet lying entirely within the minimum radius of the printing surface of blanket 16. The gripper bar 34 can have a longer seat with a steeper slant than shown in Fig. 4 so the paper will extend back from a point close to that radius.

Preferably, a second slot 64 is provided in the driven ring 69 approximately diametrically opposite the slot 63. This permits shifting the cylinder 12 lSO-degrces with respect to gear 32 so as to cause the plate to engage the blanket cylinder 11 during the part of the cycle when the platen would otherwise have engaged it. This change may be desirable for direct lithograph or for letter-press printing, as described under the heading Operation. Access to screw 62 may be facilitated by arcuate slot 65 in gear 32.

Hand wheel In preparing for a press operation or in cleaning the press afterwards, it is desirable to be able to turn the press by hand. The form of the press thus far described does not have, in conjunction with the parts so far described, a rotating shaft extending through the frame on which a hand wheel can be mounted. However, another 1:1 shaft (not shown) would be provided in this construction to mount a hand wheel and to operate throw-off mechanism represented by lever 58.

A hand wheel could be mounted elsewhere, as by using a rotating drive shaft, such as one carrying a small pinion meshing with gear 32 for driving the press. For illustration, a hand Wheel 66 has been shown.

Shields Shields 67 and 68 are preferably provided to prevent accidents such as thrusting a finger ahead of the rotating bars 33 and 34. Shield 67 may be fixed, but shield 68 should be movable to afford access to drum 11. Preferably a microswitch 69 breaks the circuit of the press driving motor whenever shield 68 is raised, to prevent operatilonlof the press when shield 68 is open, except by hand W 66 Qf course, gears and the like would also be shielded, as in common practice.

Registration feed roll unit An important feature of the present press is that the dependable uniformity of cooperation between the gripper unit 18, the blanket cylinder 11, and the plate platen cylinder 12, together with the over-all arrangement of the several elements of the press, permits feeding the sheet to the gripper unit at a point substantially separated from the cylinder 11 as seen best in Figs. 1 and 2. This in turn permits some advantageous changes in the registration feed roll mechanism, chiefly because of the fact that space is plentiful. For example, the final feeding of the sheet into the grippers may be accomplished by a feed segment 71, the length of which may be adjustable, as illustrated, if desired. Thus the feed segment 71 may include an auxiliary portion 72 which is adjustable with respect to the main or leading portion by means of a screw 73 operating through a slot in the main portion 71. Because the length of movement of the sheet under the control of the feed segment 71 is controlled by the length of this segment, no controlled operation of the pressure roller 74 to grip and release the sheet is required. Hence the pressure roller 74 may be nominally stationary, being constantly urged toward segment 71. When segment 71 passes away from roll 74, the latter moves only slightly, its support being limited in movement by a stop, the spacing as to segment 71 being adjustable. In practice, there would be a plurality of segments 71 across the width of the machine, each with its pressure roller 74, and all of which may be adjustable laterally across the width of the machine. The pressure rollers 74 may be mounted independently or on a common shaft.

The sheets may be fed to the registration feed rolls in any suitable manner, as by a suction feeder, not shown, which delivers the sheets to a biased conveyor 76 which aligns the sheets by pressing them against a side guide 77 (Fig. 2) and with this alignment feeds the sheets to the bite between segments 71 and pressure rollers 74. The lateral registration of the sheet is accomplished by the side guide 77. The longitudinal registration may be accomplished by using the bite just mentioned to stop the sheet at the desired position. Alternatively and perhaps with a little greater certainty of accuracy, the sheet could be stopped for longitudinal registration by stop fingers 80 carried by the segments 71 or their shaft 79 and extending down beside pressure roller 74. These stops should come to rest just ahead of the bite between pressure rollers 74 and segments 71, so that the sheet can get to the stops. The sheet may be urged against the stops by driven rollers 78 against which it is pressed by marbles. Some such marbles may be positioned to bear on the tapes of conveyor 76.

Shaft 79 may be driven in any suitable manner for giving it the required movement. This movement should include a smooth acceleration from its position at rest to a speed appropriate for feeding the sheet against the stop fingers 81 on the gripper bar assembly 18. The segments 71 should maintain a peripheral speed at least equal to the speed of the gripper bars until the trailing segment portions 72 have passed from pressure rollers 74 so as to release the sheet. For illustration, Figs. 1 and 2 show sectors 71 in the starting position or position of rest, although this is not in keeping with the positions of other parts of the press.

One form of drive for feeder shaft 79 is seen in Fig. 5. A cam 82 carried by gear 32 operates a lever 83 which in turn operates a link or bar 84. Member 84 may merely be pivoted to a crank arm on shaft 79 or it may include a rack portion at its end, meshing with a pinion on shaft 79. The shape of cam 32 would be somewhat different in the two instances because of the varying mechanical advantages in the case of the crank arm and the constant mechanical advantage in the case of the rack and pinion. No attempt has been made to show the exact cam shape for the illustrated form. It may be noted at this point that with the form of the invention shown in Figs. 6 and 7, where there are shafts extending through the frame, the cam 82 may be omitted, the member 84 being driven by a crank pin eccentrically positioned on the end of this shaft. In that event, however, it is not possible to have the driving movement of the member 84 stop as abruptly as with a cam and hence a greater total movement of the segments 71 will need to be provided to allow a gradual slow-down after release of the sheet. The timing of the closing of the grippers can preferably be controlled as indicated diagrammatically by slide 84.

Delivery The gripper bar to which the sheet has thus been accurately fed will carry the sheet into registration with the blanket cylinder 11. The gripper will maintain the grip on the sheet, however, and draw it away from this drum. It may be found desirable to provide stripper guides 85, to help keep the sheet drawn out. In the form of the invention shown in Figs. 1 to 4, they may be carried by bracket arms 43 and 44. When the gripper bar has reached the desired position, preferably after stripping the entire sheet from the blanket, the follower roller 39 will encounter the cam 42 and open the grippers to release the sheet. Preferably the cam 42 is adjustable over a wide range as indicated by slide 85', to vary the time of release. The sheet may then fall and slide by gravity into a pan 86 or other collecting or discharge means. One or more loosely-mounted rods 87 (Fig. l) maybeprovided for making sure that the sheets are not thrown past the collector 86. It will be observed that the sheet is thus delivered printed-side up, assuming that it was printed by the blanket cylinder 11 in an offset process. A perforated pipe 87' or a nozzle may direct compressed air against the upper face of the sheet to help strip it and move it to collector 86. The connecting hose may pass through bore 101 (Fig. 4).

If the sheet is printed by direct process so that the side facing drum 14 is printed, it is preferably delivered to the collector 88 so as to have its printed side up in this instance. In this case, cam 41 which will have been removed or shifted axially from active position during offset printing, will be placed approximately as shown in Fig. 4, so as to release the sheet in time for it to pass to the right of deflector 89 which in this instance will be shifted to the dotted line position seen in Fig. l. Deflector 89 is notched to permit gripper fingers 37 to pass through it. A stripper 90 ensures the stripping of the sheet from the printing surface on cylinder 12. Preferably, drawofl rolls 90' are provided, at least one of which is driven, to draw the sheet safely from the printing surface, once it has entered the bite between these draw-off rolls. With letter-press printing, there is usually no ditficulty in drawmg the sheet from the type. With direct lithography, if delivery into collector 88 should prove uncertain and therefore troublesome, cam 41 could be removed, deflector 89 shifted, and the sheet delivered into collector 86. In fact some models, especially table models, may be made with only collector 86. The only objection to this would be that the printed face would be down, thus causing some di ficulty of inspection.

Modification with hubless gripper cage Figs. 6 and 7 diagrammatically represent a modified form of the invention in which the gripper cage is of a hubless type and consists of the two rings 91 fastened together by the two bars 33 and 34. These rings 91 are in turn carried by peripheral type rotary bearing units 92 which consist of free turning wheels, the peripheries of which are shaped to hold, both radially and axially, the peripheries of the rings 91. Each of them is mounted on a stub shaft rigidly held in frame 27. There are three of these bearing units 92 for each of the rings 91. At least one of each group of the bearing wheels rotates on an eccentrically adjustable hub for adjustment of the tightness with which the wheels fit the rings 91. If at least two bearing wheels of each group are provided with shiftable axes, they may be used for accurately positioning rings 91.

Instead of engaging the outside of rings 91., the bearing units 92 may engage the inside edge, if preferred. With either of these arrangements, the center of rings 91 may be left open so that a shaft 93 for blanket cylinder 11 may extend through the rings to frame members 27. This construction has some advantages over the construction of Figs. 1 to 4. For example, assembly may be somewhat easier. Also the problem of obtaining sufficient rigidity in the mounting of blanket cylinder 11 is avoided, since it can be mounted in substantially the usual way. In addition, cylinder 12 may be mounted on a rotating shaft 94 which may extend through the frame members 27 to provide hand wheel 96 at one end and external cams and the like at the other end for actuating various other parts of the mechanism.

The various adjustments and movements of one cylinder with respect to the other, together with the Oldham coupling, may readily be applied to cylinder 11. This avoids any disturbances in the relationship between cylinder 12 and its inking and dampening assemblies. Cylinder 11 is then driven by a gear 97 (through an Oldham coupling if the cylinder 11 is shiftable) which meshes with gear 32. The gear 32 is in this instance sufficiently wide to mesh also with gear ring 98 carried by the adjacent ring 91 of the gripper cage. Of course two narrow gears 32 could be provided in place of one wide gear.

Figs. 6 and 7 are considerably simplified by the omission of parts. For example, gripper opening earns 41 and 42 have been omitted for simplicity. In this instance, these cams could be carried directly by a frame member 27 by means of brackets extending in through a ring or rings 91. Alternatively, the shaft 36 which actuates the grippers or the crank arm 38 thereon could extend outside the gripper cage to be operated by cams outside of the cage. Space for this is most easily found on the side remote from the gears, namely, the side at the top of Fig. 7. This would add torque drag at that side however, and is not preferred at present.

Assembly The form of the invention shown in Figs. 6 and 7 needs very little discussion of the assembly except to note that the cage 20 is put in place while some of the rollers 92 are removed and before the shaft 93 for cylinder 11 is inserted.

In the assembly of the form shown in Figs. 1 to 4, the cylinder 11 is mounted in bracket arms 43 and 44 before this unit is mounted on a frame. After insertion of shaft 48 and after mounting of gears 49 and 52, gear wheel 19 is applied over one stub shaft 26 and the other wheel 19 over the other stub shaft. The gripper carrying bar 34 and the bar 33 may previously have been rigidly secured to the gear wheel 19 and may now be secured to the other wheel 19. This entire assembly is now secured to the frames. If a splined connection of stub shaft 26 to the frame is used, the frame member on one side of the machine will have to be left unattached to the remainder of the frame until the splines have been slipped in place.

Operation Although the operation of the press will be relatively evident from the previous description, a brief explanation of its operation may be helpful.

In the case of offset printing, a properly etched or otherwise treated plate 17 is applied to the plate-carrying portion 13 of cylinder 12. The press may be rotated with the main cylinders spaced apart until the plate is properly inked by running successively against the form rollers of the dampening and inking units 22 and 23. A

pile of sheets to be printed will have been placed on the primary feeder, not shown. When it is started, sheets will be delivered to conveyor board 76 in properly-timed relation to the operation of the press. The sheets will be laterally registered by side guides 77 and will come to rest against stops 80 or the alternative stop means comprising the bite between segments 71 and pressure rollers 74. At the proper time during each cycle of the press, segment 71. will be pivoted by means of cam 82 in Fig. and will feed the sheet into the gripper unit 18 as the latter approaches the uppermost portion of its orbit. The gripper 18 will carry the sheet into the bite between cylinders 11 and 12. The sheet may be carried over guides (not shown), if desired, but this is believed not necessary because the turning of the leading edge of the sheet tends to bow the paper upwardly and avoid premature contact with cylinder 11. In the meantime, the blanket on cylinder 11 will have received an ink impression from plate 17 with which it will print the adjacent face of the sheet, the opposite face of the sheet supported by platen 14. Cam 41 having been removed, the gripper will carry the leading edge of the sheet to the far side of cage 20, stripping the sheet from the blanket. Cam 42 will then release gripper fingers 37 so that the sheet will be deposited in collector 86.

For direct printing with the same gripper unit 18 and the same timing of the feed of the sheet, screw 62 in Fig. 3 will be removed and cylinder 12 rotated approximately 180 degrees after which screw 62 will be replaced, this time passing through slot 64 instead of slot 63, from which it was removed. The platen 14 with its cams 100 need not be touched as the cams will throw the form rolls out as before. The offset plate 17 will be replaced with a direct lithograph plate or a suitable relief plate. When properly inked, it will print directly on the adjacent face of the sheet. Cam 41 in Fig. 4 will be applied so that the gripper will release the sheet in time for it to pass to the right of deflector 89 (swung to the dotted line position of Fig. 1) and it will be delivered to the collector 88 printed face up.

Both portions of roll 12 may be used for direct printing if two gripper units 18 are provided and a sheet fed to each, and no cams used. Thus if two different direct plates are used, a two-page letter or form may be printed and collated.

Additional features and advantages Although, for purposes of simplification, the shaft 48 in Fig. 3 has been shown with a relatively simple type of mounting, it may, if preferred, have the more complex type of mounting illustrated for the shaft 57, the shaft then being stationary except for adjustment and throwout movements. This may be preferred in order to leave the cylinder 12 invariable as to its axis. The chief problem in providing the shaft 48 with the shiftable axis is to control said shaft. This can be accomplished, however, by providing a bore 101 in one or both of stub shafts 26 through which a control member may be passed to operate gears or links for turning the shaft 48 for throwout and pressure adjustment purposes. If the shaft 48 is to be shiftable, the gear 49 would be positioned between drum 11 and bracket 44, being carried on a bushing similar to bushing 56 and being connected to the cylinder 11 through an Oldham coupling. Gear 49 would then be connected to gear 51 through a pair of gears on a common shaft, the common shaft passing through and being journaled in bracket 44.

It will be observed that with both illustrated forms of the invention, there is very little torque resisting the rotation of the ring 91 or wheel 19 more remote from the driving teeth 31 or gear 98. This torque is only the frictional torque of its mounting and the torque resulting from a part of the pull exerted on the sheet. It is believed therefore that providing sufficient rigidity in the cage 20 so that this wheel or ring will not appreciably lag behind its more directly driven counterpart will present no problem. It may be noted, however, that, if found necessary, gears may be provided on both sides of the gripper cage.

It will be observed that the upper portion of both cylinders 11 and 12 are thoroughly accessible with both illustrated forms of the press. This is a highly desirable feature because it facilitates cleaning and otherwise servicing the cylinders. It should be understood that with some types of short-run printing, it may be necessary to clean the blanket cylinder quite frequently and also to put on and take off plates frequently.

The cylinders have been shown arranged with their axes approximately in a horizontal plane. This provides exceptionally good accessibility from above. In addition, it facilitates moving the paper generally horizontally toward the press in the preliminary feeding without obstructing accessibility to the upper side of the blanket cylinder. Nevertheless it may be desirable in some instances to shift the relative positions of the axes. For example, raising the top of cylinder 11 to the level of the top of cylinder 12 as seen in Fig. 5A still affords equally good accessibility from above while leaving more room for a collector below. This is especially suitable in the case of a model designed to rest on a table. The axis of cylinder 11 can be raised to the level of the top of cylinder 11 without excessively impairing access but must not be so high that the gripper cannot deliver the sheet reliably after stripping it. Accessibility is impaired somewhat as the axis of cylinder 11 is lowered below the level of the axis of cylinder 12, but the impairment 1s not too serious until the bottom of the cylinder 11 is lower than the bottom of cylinder 12.

The pile from which sheets are drawn may be positioned close to cylinder 11 as seen in Fig. 5A. In that event, the feeder preferably delivers sheets to rollers 78 of the illustrated feed roll mechanism. However, the feed roll mechanism could be omitted with this type of press at least as well as with other presses, the initial feeder then feeding directly to the gripper unit 18.

Although the cage has been illustrated as including bearing means at each end of the cage, it could at least 1n theory include a bearing means at one end of the cage only, the gripper bar extending from that end being unsupported at its far end. Likewise it may be observed that the bearing means at the two ends may be different. For example, the driven end of the cage may be in the form of a wheel supported by stationary stub shaft as in Fig. 3 while the support at the far end may be by an open-centered ring supported by peripheral rollers as in Fig. 6. 'In that event, it will probably be sufficient for the peripheral rollers to give only radial support to the ring, not axial support.

The term printing press is used in the accompanying claims in its broad inherent sense, including all machines making multiple copies by applying ink to sheets and is intended to include the smaller types of machines sometimes called oflice duplicators as well as larger printing presses. Although the invention in its simplified form is especially suitable for office duplicators, it has important advantages, especially in more complex forms,

for large printing presses.

It will be understood that the press will be driven by a motor. Thus gear 32 may be driven by a pinion which may be driven by a belt driven by the motor.

I claim:

1. A printing press including a frame, a stationary stub shaft member carried by the frame and securely anchored thereto, first and second cylinders arranged for rotation with their peripheries moving together in adjacent relation, a rotary rigid cage containing the second cylinder and rotatable in the same direction as the second cylinder about an axis eccentric to the second cylinder axis, the circumference of the cage being larger than the circumference of the second cylinder, a wheel forming an end member of the cage and rotating on said stub shaft, an extension bracket arm on said shaft between said wheel and the second cylinder, means carried by said bracket arm for rotatably mounting the second cylinder, a paper gripper on the cage movable thereby through and away from the bite between the first and second cylinders; and means for driving the cylinders and cage in timed relation with the circumferential speeds of the cylinders equal to each other and approximately equal to the speed of the gripper.

2. A printing press including a frame, a bracket extending across the frame and terminating with stationary stub shaft members supported by the frame and at least one of which is anchored securely to the frame, first and second cylinders arranged for rotation with their peripheries moving together in adjacent relation, a rotary rigid cage containing the second cylinder and rotatable in the same direction as the second cylinder about an axis eccentric to the second cylinder axis, the circumference of the cage being larger than the circumference of the second cylinder, wheels forming end members of the cage and rotating on said stub shafts, extension bracket arms on said shafts between said wheels and the second cylinder, means carried by said bracket arms for rotatably mounting the second cylinder, a paper gripper on the cage movable thereby through and away from the bite between the first and second cylinders adjacent the first cylinder, and means for driving the cylinders and cage in timed relation whereby the circumferential speeds of the cylinders are equal to each other and approximately equal to the speed of the gripper.

3. A printing press including a frame, a stub shaft member supported by the frame, first and second cylinders arranged for rotation with their peripheries moving together in adjacent relation, a rotary rigid cage containing the second cylinder and rotatable in the same direction as the second cylinder about an axis eccentric to the second cylinder axis, the circumference of the cage being larger than the circumference of the second cylinder, a wheel forming an end member of the cage and rotatably carried by said stub shaft, a bracket supported at one end by said shaft and at the other end by the frame on the far side of the press and rigidly anchored to the frame at one end, an extension bracket arm between said wheel and the second cylinder rigid with said bracket, means carried by said bracket arm for rotatably mounting the second cylinder, a paper gripper on the cage movable thereby through and away from the bite between the first and second cylinders; and means for driving the cylinders and cage in timed relation with the circumferential speeds of the cylinders equal to each other and approximately equal to the speed of the gripper.

4. A printing press comprising first and second cylinders, means for mounting said cylinders for rotation with their peripheries moving together in adjacent relation, a rotary rigid cage containing the second cylinder and rotatable in the same direction as the second cylinder about an axis eccentric to the second cylinder axis, the circumference of the cage being larger than the circumference of the second cylinder, a paper gripper on the cage movable thereby through and away from the bite between the first and second cylinders, a paperadvancing device adjacent the path of the gripper and remote from the main cylinder, for advancing sheets into the gripper, and means for driving the cylinders and cage in timed relation with the circumferential speeds of the cylinders equal to each other and approximately equal to the speed of the gripper, including a pressure roll, a sector cooperating therewith and of the right length for feeding a sheet to the passing gripper and releasing it by leaving the pressure roll by continuation of the feeding movement, the surface of the pressure roll being constantly urged toward the sector-engaging posi tion.

5. A printing press including a combined plate and platen roll, a blanket roll of smaller diameter, means for driving the blanket roll with an integral number of revolutions greater than one for each revolution of the combined roll, a rotary rigid cage surrounding the blanket roll and including a gripper for carrying a sheet through the bite between the rolls, and a registration sheet advancing unit for feeding sheets to the gripper at a point substantially spaced from the combined roll, said blanket roll being positioned with its axis in the zone between the level of the top and the level of the axis of the combined roll, said sheet-advancing unit including idler rollers adjacent the path of the gripper and registration means for stopping a sheet fed thereto and including sectors pivotally mounted to cooperate with the surfaces of said rolls on a side remote from the path of the gripper for feeding the sheet to the gripper, means for driving the sectors in timed relation with the rolls and rings, for pivoting the sectors to a position of rest to permit a sheet to be fed to the stop position, and pivoting to feed the sheet into the gripper, and pivoting further in the same direction to release the sheet from the idler rollers.

6. A sheet-advancing unit for a printing press and the like, including a pivotally mounted sector, a rotatable pressure roller constantly urged toward sector-engaging position, and means for driving the sector in one direction to a position of rest and in the other direction to feed the sheet and to pass out of engagement with the pressure roller to release a fed sheet; said sheet-advancing unit including means effective when the sector is in its position of rest for stopping a sheet in predetermined position to be fed by the sector in registration with the sector when the sector is pivoted.

7. A printing press including larger and smaller cooperating printing cylinders, a gripper, means carrying the gripper between the cylinders and around and away from the smaller cylinder and sheet-advancing means near the path of the gripper and remote from the larger cylinder for advancing a sheet into the gripper; the smaller cylinder being positioned with its bottom at least as high as the bottom of the larger cylinder and its axis at least as low as the top of the larger cylinder, a guard over the path of the gripper between the sheet-advancing means and the cylinders and movable to an open position, means for driving the press and means actuated by opening the guard and controlling the press drive means for stopping the press.

8. A printing press including a single pair of printing cylinders rotatable about horizontal axes and in tangential relation to form a bite, one of said cylinders being an offset transfer cylinder and the other cylinder having twice the diameter of the transfer cylinder, a sheet gripper, means arranged for carrying the gripper through a path encompassing the smaller cylinder and passing through the bite and thereafter away from the smaller cylinder, means for thereafter opening and closing said gripper, sheet supporting and registering feed means located adjacent to the path of the open gripper while said path is spaced from the smaller cylinder, the feed means being widely spaced from the larger cylinder with a full width space therebetween for ready manual access to a portion of the surface of the smaller cylinder facing generally upwardly, by reaching between the feed means and the larger cylinder; and inking and dampening means arranged to engage a portion only of the circumferential area of the larger cylinder thereby permitting unrestricted access to a substantial area thereof.

9. A printing press according to claim 8 in which the gripper and the means for carrying it form a rigid cage.

10. A printing press according to claim 8 having a readily movable guard normally obstructing access through said space.

11. A printing press according to the preceding claim having power means for driving the press and means effective when the guard is opened to render ineffective the power drive of the press.

12. A printing press according to claim 8 in which the gripper and feed arrangement are such that one sheet is carried through the bite for each revolution of the larger cylinder.

13. A printing press according to claim 8 in which the axis of the smaller cylinder is no higher than the top of the larger cylinder.

14. A printing press according to claim 8 in which the path of the gripper is equal in length to the circumference of the larger cylinder.

15. A printing press according to claim 8 in which the gripper follows a path which maintains a sheet out of contact with the smaller cylinder from the feed means substantially to the bite.

16. A printing press including a single pair of printing cylinders rotatable about horizontal axes and in tangential relation to form a bite, one of said cylinders being an offset transfer cylinder and the other cylinder having twice the diameter of the transfer cylinder, a sheet gripper, means arranged for carrying the gripper through a path encompassing the smaller cylinder and passing through the bite and thereafter away from the smaller cylinder and thereafter moving in a direction to present uppermost that face of the sheet which engaged the smaller cylinder, means for thereafter opening and closing said gripper, sheet supporting and registering feed means located adjacent to the path of the open gripper While said path is spaced from the smaller cylinder, the feed means being widely spaced from the larger cylinder with a full width space therebetween for ready manual access to a portion of the surface of the smaller cylinder facing generally upwardly, by reaching between the feed means and the larger cylinder; and inking and dampening means arranged to engage a portion only of the circumferential area of the larger cylinder thereby permitting unrestricted access to a substantial area thereof.

17. A printing press including a single pair of printing cylinders rotatable about horizontal axes and in tangential relation to form a bite, one of said cylinders being an offset transfer cylinder and the other cylinder having twice the diameter of the transfer cylinder, a sheet gripper, means arranged for carrying the gripper through a path encompassing the smaller cylinder and passing through the bite and thereafter away from the smaller cylinder and thereafter movingin a direction to present uppermost that face of the sheet which engaged the smaller cylinder, means for thereafter opening and closing said gripper, sheet supporting and registering feed means located on the same side of the vertical axial plane of the smaller roller as is the point of opening the gripper and located adjacent to the path of the open gripper while said path is spaced from the smaller cylinder, the feed means being widely spaced from the larger cylinder with a full width space therebetween for ready manual access to a portion of the surface of the smaller cylinder facing generally upwardly, by reaching between the feed means and the larger cylinder; and inking and dampening means arranged to engage a portion only of the circumferential area of the larger cylinder thereby permitting unrestricted access to a substantial area thereof.

18. A printing press including a single pair of printing cylinders rotating together to form a bite, one being an offset transfer cylinder and the other being twice its diameter and having one sector for holding printing medium and another sector providing an impression surface, both sectors cooperating with the same portion of the smaller cylinder; a sheet feeding guide surface readily accessible for hand feeding of sheets along the guide surface; sheet gripper means following a path substantially of a length equal to the circumference of the larger cylinder and encompassing one of the cylinders; the gripper means passing through the bite, moving away from the smaller cylinder and downwardly, thereafter passing adjacent the guide surface after passing the point in the path most remote from the bite; means for opening the gripper means after the gripper means moves from the smaller cylinder and closing the gripper means to seize a sheet from the guide surface; means for selectively positioning the sheet holding gripper means and the two segment positions of the cylinder relatively for causing the sheet to engage either one of the segments, depending on whether direct or offset printing is desired; with peripheral adjustability of at least the sector carrying the printing medium in either case; the top of the encompassed cylinder being substantially at least as low as the top of the unencornpassed cylinder; the guide surface being substantially spaced from the bite and from the unencornpassed cylinder, a substantial and generally upwardly facing part of the encompassed cylinder being readily accessible across the full printing width thereof by manually reaching between the guide surface and the unencornpassed cylinder; and said unencornpassed cylinder being readily accessible along its cylindrical surface, including a generally upwardly facing part thereof, from the bite upwardly substantially to the vertical plane of its axis; inking and damping means engaging the larger cylinder elsewhere than in said specified areas of accessibility; and said press including means for stripping sheets from either cylinder and presenting them for inspection.

References Cited in the file of this patent UNITED STATES PATENTS 1,307,969 Harris June 24, 1919 1,401,423 Meisel Dec. 27, 1921 1,440,787 Meisel Jan. 2, 1923 1,597,941 White Aug. 31, 1925 2,108,800 Davidson Feb. 22, 1938 2,406,205 Davidson et al. Aug. 20, 1946 

